The present application is based on Japanese Priority Document 2000-274457 filed on Sep. 11, 2000, the content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a line printer which performs printing by using a line head such as a thermal head, an ink jet head or the like.
2. Discussion of the Background
There has heretofore been known a proposal wherein in a line printer using a thermal head as in a facsimile or the like, the thermal head is driven divisionally in a main scan direction to thereby hold low, power consumption for driving the thermal head even when print data set every lines increase, whereby the capacity of a power supply is reduced. However, a problem arises in that since the thermal head is driven on a division basis even when print data (number of dots) set for each line decreases, a print velocity becomes slow.
With the foregoing in view, there has been a proposal wherein a division number for driving a thermal head is set according to the plentiness or degree of the number of dots to thereby achieve a reduction in power consumption and the speeding up of printing, as described in Japanese Patent Provisional Publication (Kokai) No. Hei 5(1993)-201053.
The proposal described in Japanese Patent Provisional Publication (Kokai) No. Hei 5(1993)-201053 is excellent in terms of the speeding up of the printing as compared with the proposals made prior to it. However, since a print velocity in a sub-scan direction, i.e., a paper feed velocity is constant even if a division number for divisionally driving the thermal head decreases or increases, there is a limit to the speeding up of the printing.
In certain embodiments, there is a line printer capable of satisfying a reduction in power consumption and achieving the speeding up of printing.
According to embodiments of the present invention, a printer detects print data areas set in one-block units with white lines as boundaries, calculates division numbers for divisionally driving a line head in every area, extending in its main scan direction to thereby output print data when the numbers of dots set in every line in the print data areas exceed the maximum number of printable dots set by a head drive unit, detects maximum division numbers in the print data areas, sets paper feed velocities in inverse proportion to the maximum division numbers respectively, and executes printing in the print data areas set in the one-block units on the condition that the line head is divisionally driven with the maximum division numbers and paper is conveyed at the set paper feed velocities.